Separable fastener assembly



July 19. 1966 c. K. BROWN 3,261,261

SEPARABLE FASTENER ASSEMBLY Original Filed Dec. 28. 1961 2 Sheets-Sheet1 INVENTOR. CLARENCE K. 5

BY Ms 7 m ATT'QZ/VEYJ.

July 19. 1966 c. K. BROWN SEPARABLE FASTENER ASSEMBLY Original FiledDec. 28, 1961 2 Sheets-Sheet 2 FIG. 6

IN VENTOR. CLA REA/CE A. BROWN A TTOR/VE'YS.

United States Patent 3,261,261 SEPARABLE FASTENER ASSEMBLY Clarence K.Brown, Long Beach, Calif., assignor to Hi- Shear Corporation, Torrance,Calif., a corporation of California Continuation of application Ser. No.162,718, Dec. 28, 1961. This application Mar. 9, 1965, Ser. No. 441,407Claims. (Cl. 891) involves the risk of damaging neighboring structure,be-

cause the charge must be large enough to be sure to effect the fracture,or, in theevent the charge is not large enough, there is the risk thatseparation might not occur.

It-is an object of this invention to provide apparatus for joining andaccomplishing the separation of a pair of assemblies in which theseparation can be effected by explosive means, but in which theexplosive means need only overcome the resistance of a shear pin whosestrength need not be as great as the main-bearing parts of the fastener,and which can be precisely determined. Then a minimal charge can beused, and risk of damaging neighboring structure, and of failure toseparate, are significantly reduced.

It is an optional object of the invention to include thruster means insuch apparatus to provide positive separation of the joined assemblies.

-It is still another optional object of the invention to providepin-pulling means for pin-detent fastener mechanisms.

Apparatus according to the invention comprises a body attachable to oneof a pair of assemblies to be separably joined. The body has an internalcylinder, and a piston slidedly fitted in the cylinder adapted to engagethe other of the assemblies. 'A shear pin interconnects the piston andthe body, and holds them against relative axial movement until shearedby sufiicient force applied to the piston. Explosive means are providedin fluid communication with the cylinder, which is adapted to dischargegas under pressure into the cylinder to shear the shear pin and move thepiston and cylinder relative to each other to disengage the assemblies.

According to a preferred but optional feature of the invention, thepiston is attached directly to its respective assemblyso as to drive theassemblies apart when the explosive means is actuated.

According to still another preferred but optional feature of theinvention, the piston comprises a pin which makes a keying connectionwith its respective assembly, whereby upon actuation of the explosivemeans, the pin is pulled to release the assemblies.

The above and other features of this invention will be fully understoodfrom the following detailed description and the accompanying drawings,in which:

FIG. 1 is a side elevation, partly in cutaway crosssection showing anembodiment of the invention is assembly-joining position;

FIG. 2 is a cross-section taken at line 2-2 of FIG. 1;

FIG. 3 is a View as in FIG. 1, but with the device in separatedposition;

FIG. 4 is a side elevation, partly in cutaway crosssection, showing thepreferred embodiment of the invention in assembly-joining position;

3,261,261 Fate-med July 19, 1966 ice FIG. 5 is a cross-section taken atline 5-5 of FIG. 4;

FIG. 6 is a view as in FIG. 4, but with the device in separatedposition; and

FIG. 7 is a fragmentary cross-section of a modification of the device ofFIG. 4.

FIG. 1 illustrates a pin-puller type device wherein two assemblies 10,11 are joined. Bolt 12 attaches assembly 16 to body 13, and an insert 14having a cross port 15 fits in hole 16 in the body for attachingassembly 11 to the body.

The body has a neck portion 17 which encloses a cylinder 18 which has anaxis 19. A cap 20 closes the right hand end of the cylinder. A vent 21passes through the cap.

A ring 22 of deformable material is held in the cylinder by the cap. Thematerial is deformable in the sense that it can be permanently deformed.Crushing is an example of such permanent deformation. A suitablesubstance is 2S0 Aluminum. Energy dissipated in deforming the materialwill not be conducted to the body as a shock, and this aids inprotecting surrounding assemblies from sharp forces which wouldotherwise be exerted by the pistons slamming against the cap.

A piston 23 carries an O-n'ng 24 for sealing with the cylinder. Thepiston is axially movable in the cylinder. A rod 25 forms a continuationof the piston, and passes through the body, through hole 16, and intohole 26.

A shear pin 27 joins the body and piston in the position illustrated byFIG. 1. It holds the body and piston against relative axial movement,and is in full bearing in the holes so as to provide an effective,reliable, and predictable safety means which will withstand loads belowits design limit, and yield to free the device at the design limit.

A squib port 28 is in fluid communication with cylinder 18 and receivesa squib 29. The squib contains explosive means 30 actuable by a signal,usually an electric current applied to a bridge wire 31 in contact withthe explosive inside the squib.

A collar 32 on the piston limits its movement to the left.

In FIG. 4, there is shown the presently preferred embodiment of theinvention used to join assemblies 50, 51 together. This device includesa body 52 with external threads 53 which are adapted to be threaded intointernal threads 54 in assembly 51. A locknut 55 locks the assembly 51and body 52 together.

A cylinder 56 extends along axis 57 into the body from first end 58thereof. The body includes a threaded squib port 59 which is in fluidcommunication with cylinder 56. It receives an externally threaded squib60, which squib includes explosive means 61 such as a charge ignitableby a signal, for example an electric current passed through bridge wire62 in contact with the charge. In this squib, as in squib 29 in FIG. 1,leads 63 may be provided for conducting electric current to the bridgewire.

A piston 64 is slidably fitted in the cylinder and bears an O-ring 65for fluidly sealing with the cylinder. The piston includes attachmentmeans 66 in the form of an internally threaded opening in the end of thepiston adjacent to first end 58 of the body. This is for the purpose ofreceiving means such as bolt 67 for attaching assembly 50 to the piston.

A shear pin 68 joins the piston and the body together in full bearingcontact in the holes and holds them assembled in the position shown inFIG. 4. This pin holds the load, and is accurately sized relative to itsinherent strength so as both to hold the design load, and to yield atthe design force from the squib.

In FIG. 7, piston 64 is shown receiving the end of a stepped bolt 100.The bolt has an enlarged shank with a diameter adapted to fit in hole101 in assembly 102.

The diameter of hole 101 is greater than the diameter of the piston, soas to avoid the risk of the pistons hanging up instead of passingstraight through assembly 102. This modification is useful when it isnot desired to thrust assemblies 102 and 103 apart, and when it is notobjectionable to free the piston from the assemblies.

The operation of the device of FIGS. 13 will be readily understood fromthe drawings. Assemblies and 11 are held together by piston 23, and theycannot be separated unless it is withdrawn. To withdraw the pin, thesquib is fired, which will move the piston to the right, withdrawing itto the position shown in FIG. 3. This enables the assembly 11 and itsinsert 14 to fall away from the body. It will be noted that no loosepiece are generated, and that all of the fastener system goes withrespective assemblies. As soon as the force is sufiiciently great, theshear pin is sheared and the pin is withdrawn.

When the piston reache the position shown in FIG. 3, it deforms ring 22,thereby dissipating some or all of the kinetic energy of the piston, andreducing the shock on the assembly pin which otherwise would be directlytransmitted from the piston through the body.

It will be noted that this device is reusable =by unthreading the cap,replacing the ring, the squib, and the shear pin. Ring 22 is optionaland used only in the event that it is desired to minimize shock on thesurrounding structure.

The operation of the device of FIGS. 4-6 is similar. The devices arefirmly held together by the attachments shown until the shear pin issheared. This is accomplished by firing the squib which forces thepiston to the left. This shear the shear pin and then, of greatimportance in this particular embodiment, it shoots the two assembliesapart by firmly expelling the piston from the cylinder. As in the deviceof FIGS. 13, all parts are retained to the assemblies and no loose partsare scattered around. It will also be observed that this device ireusable by replacing the shear pin and the squib.

The device of FIG. 7 functions like that of FIG. 4, except that thepiston and the stepped bolt are fired away from the assemblies, and theassemblies are not thrust apart.

This invention thereby provides means for reliably joining bodiestogether and for separating them by the application of minimal forceswhich can be closely related to the strength of the simple pin to besheared.

The invention provides additional advantages of pinpuller typeseparations and also of positive separation of the assemblies.

This invention is not to be limited by the embodiments shown in thedrawings and described in the description which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

I claim:

1. Apparatus for joining and accomplishing the separation of a pair ofassemblies, comprising: a body having an internal cylinder; a pistonslidably fitted in said cylinder; a rod attached to the piston andextending longiverse to said cylinder, said rod being adapted to entersaid port; attachment means On said body for attachment to one of saidassemblies; engagement means on the other assembly adapted to enter saidport to be releasably engaged by said rod, a shear pin seated in fullbearing contact in and interconnecting the rod and body, and being sodisposed and arranged as to hold them against relative axial movementuntil sheared by sufficient force applied to the piston to accomplishsaid shearing and cause said axial movement; and explosive means influid communication with the cylinder adapted to discharge gas underpressure, on the side of the piston adjacent to the end of the cylindercloser to said assemblies, thereby to push said piston and draw said rodcompletely free from the engagement means, the length of the cylinderbeing adequate to provide for sufficient rod movement to free theengagement means; a vented oap enclosing the other end of the cylinder;and a barrier of permanently deformable material, the barrier materialbeing more easily permanently deformed than the material of the cap,said barrier being held in the path of said piston so as to dissipatekinetic energy of the piston in the substantially non-resilientdeformation of the material of the barrier by the piston when theexplosive means is fired and the cylinder thereafter strikes thebarrier.

2. Apparatus according to claim 1 in which said engagement meanscomprises an internally threaded, crossported insert adapted to beattached to its respective assembly by its threads, and to pass the rodthrough its cross port, the rod engaging the body on both sides of theinsert prior to firing the explosive means.

3. Apparatus according to claim 1 in which the explosive means is asquib in a threaded housing and in which an internally threaded port isformed in the body to receive the housing, and to permit the squib todischarge into said body.

4. Apparatus according to claim 1 in which the explosive means is asquib.

5. Apparatus according to claim 4 in which said engagement meanscomprises an internally threaded, cross-ported insert adapted to beattached to its respective assembly by its threads, and to pass the rodthrough its crossport, the rod engaging the body on both sides of theinsert prior to firing the explosive means.

References Cited by the Examiner UNITED STATES PATENTS 2,497,084 2/1950Irby 89---1 2,499,379 3/1950 Garrett 891 2,732,765 1/1956 Boyd 891.52,873,648 2/1959 Musser et al. 89-1 2,966,200 12/1960 Fredhold 15S--93,024,592 3/1962 Leaman 891.5 X

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL W. ENGLE, Examiner,

1. APPARATUS FOR JOINING AND ACCOMPLISHING THE SEPARATION OF A PAIR OFASSEMBLIES, COMPRISING: A BODY HAVING AN INTERNAL CYLINDER; A PISTONSLIDABLY FITTED IN SAID CYLINDER; A ROD ATTACHED TO THE PISTON ANDEXTENDING LONGITUDINALLY THEREFROM; A PORT IN SAID BODY DISPOSEDTRANSVERSE TO SAID CYLINDER, SAID ROD BEING ADAPTED TO ENTER SAID PORT;ATTACHMENT MEANS ON SAID BODY FOR ATTACHMENT TO ONE OF SAID ASSEMBLIES;ENGAGEMENT MEANS ON THE OTHER ASSEMBLY ADAPTED TO ENTER SAID PORT TO BERELEASABLY ENGAGED BY SAID ROD, A SHEAR PIN SEATED IN FULL BEARINGCONTACT IN AND INTERCONNECTING THE ROD AND BODY, AND BEING SO DISPOSEDAND ARRANGED AS TO HOLD THEM AGAINST RELATIVE AXIAL MOVEMENT UNTILSHEARED BY SUFFICIENT FORCE APPLIED TO THE PISTON TO ACCOMPLISH SAIDSHEARING AND CAUSE SAID AXIAL MOVEMENT; AND EXPLOSIVE MEANS IN FLUIDCOMMUNICATION WITH THE CYLINDER ADAPTED TO DISCHARGE GAS UNDER PRESSURE,ON THE SIDE OF THE PISTON ADJACENT TO THE END OF THE CYLINDER CLOSER TOSAID ASSEMBLIES, THEREBY TO PUSH SAID PISTON AND DRAW SAID RODCOMPLETELY FREE FROM THE ENGAGEMENT MEANS, THE LENGTH OF THE CYLINDERBEING ADEQUATE TO PROVIDE FOR SUFFICIENT ROD MOVEMENT TO FREE THEENGAGEMENT MEANS; A VENTED CAP ENCLOSING THE OTHER END OF THE CYLINDER;AND A BARRIER OF PERMANENTLY DEFORMABLE MATERIAL, THE BARRIER MATERIALBEING MORE EASILY PERMANENTLY DEFORMED THAN THE MATERIAL OF THE CAP,SAID BARRIER BEING HELD IN THE PATH OF SAID PISTON SO AS TO DISSIPATEKINETIC ENERGY OF THE PISTON IN THE SUBSTANTIALLY NON-RESILIENTDEFORMATION OF THE MATERIAL OF THE BARRIER BY THE PISTON WHEN THEEXPLOSIVE MEANS IS FIRED AND THE CYLINDER THEREAFTER STRIKES THEBARRIER.